1. Volume 16, Issue 11, Pages 2864-2874 (September 2016)
Oscillatory Dynamics in the Frontoparietal Attention Network during Sustained Attention in the Ferret 
Kristin K. Sellers, Chunxiu Yu, Zhe Charles Zhou, Iain Stitt, Yuhui Li, Susanne Radtke-Schuller, Sankaraleengam Alagapan, Flavio Fröhlich 
Cell Reports 
Volume 16, Issue 11, Pages (September 2016)
DOI: /j.celrep
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2. Cell Reports 2016 16, 2864-2874DOI: (10.1016/j.celrep.2016.08.055)
Copyright © 2016 The Author(s) Terms and Conditions

3. Figure 1
Animals Performed a Sustained Visual Attention Task during Simultaneous Electrophysiological Recordings in Prefrontal Cortex and Posterior Parietal Cortex
(A) Top: the 5-CSRTT was a self-paced task. The animal initiated each trial at the lick spout starting a 5-s sustained attention period, after which a stimulus appeared in one of five windows. Correct responses resulted in delivery of a water reward. Bottom: The electrophysiological signals were continuously recorded to provide LFP and spiking activity information.
(B) Behavioral chamber with five response windows on a touch screen at one end and a lick spout at the other end.
(C) After training, animals performed at approximately 80% of trials correct per session. Behavioral performance for Animal C is shown, see Figure S1 for other animals.
(D) Raster plots of two SUs each in PFC and PPC aligned to trial initiation show task modulation in firing rate. The units showed heterogeneous changes in firing rate across time.
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4. Figure 2
Anterograde and Retrograde Tracing Demonstrate Anatomical Connectivity between PFC and PPC
See Figure S2 for additional animals.
(A) rAAV5-CamKII-GFP was injected in PFC for anterograde tracing (solid circle). The expression was assessed in PPC (dashed circle). The arrow indicates the direction of the anatomical connections elucidated.
(B) GFP was injected in PFC at 27 mm relative to caudal crest (rcc). The red square in the neighboring section stained for Nissl indicates the location of the fluorescent image on the right. The injection site in PFC shows robust labeling of cell bodies; green = GFP, blue = DAPI counterstain, ASG = anterior sigmoid gyrus, PRG = proreal gyrus.
(C) Cytochrome oxidase stained neighboring section in PPC (13.5 mm rcc). The red square indicates the location of the fluorescent image on the right. The projections in PPC exhibit GFP labeling, indicating direct anatomical connections from the injection site location; SSG = suprasylvian gyrus, LG = lateral gyrus.
(D) CTB-488 was injected in PPC for retrograde tracing (solid circle). The expression was assessed in PFC (dashed circle). The arrow indicates the direction of the anatomical connections elucidated.
(E) CTB-488 was injected into PPC. The red square in the neighboring section stained for cytochrome oxidase indicates the location of the fluorescent image on the right.
(F) PFC exhibits expression of CTB-488. The red square in the section stained for Nissl indicates the location of the fluorescent image on the right.
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5. Figure 3
Task-Dependent Modulation of Single Unit Spiking and Spectral Activity
(A) Left: 86.7% of PFC units across all animals showed significant modulation during the peristimulus period (−5 to 7 s relative to trial initiation). The colored pie pieces indicate significantly modulated units for each animal, while the gray pieces show units with non-significant modulation. Right: The distribution of the largest break point for each significantly modulated PFC unit is shown. Structural change in spiking activity was most prominent during the sustained attention period. The dashed lines indicate trial initiation and stimulus onset times.
(B) Left: 85.1% of PPC units across all animals exhibited significant modulation during the peristimulus period. The colors are as in (A). Right: In PPC, the distribution of the largest break point for each significantly modulated unit is shown. Structural change in spiking activity was most prominent immediately following trial initiation and at stimulus onset.
(C) Spectra show average power before initiation (−5 to 0 s relative to initiation), after initiation (0 to 5 s relative to initiation), and after touch (0 to 5 s relative to touch). Left: PFC exhibited 1/f structure with little spectral modulation. Right: In PPC, a prominent 5 Hz peak was evident before and after trial initiation, but not following touch. The insets show example LFP activity filtered in the theta frequency band.
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6. Figure 4
Effective Connectivity and Task-Dependent Synchronization between PFC and PPC at 5 Hz
(A) LFP-LFP phase locking was used to assess synchronization between PFC and PPC. At behaviorally relevant periods during the behavior task (before initiation = −3 to −1 s relative to initiation, during initiation = −0.5 to 0.5 s relative to initiation, after initiation = 1 to 3 s relative to initiation, and after touch = 1 to 3 s relative to touch) phases in PFC and PPC were assessed for consistent differences. Here, the phase at 5 Hz is shown for one pair of channels across trials.
(B) PLV was highest at 5 Hz.
(C) Averaged for Animal A, phase locking between PFC and PPC was prominent before and after trial initiation, weakened during trial initiation and by stimulus onset, and effectively abolished following touch. See Figure S4 for other animals.
(D) Phase locking values before initiation (left) and after initiation (right) were significantly greater than after touch (p values for paired t test). Each dot represents one recording session.
(E) Phase locking values before initiation (left) and after initiation (right) were significantly greater than during initiation (p values for paired t test).
(F) The phase difference between PFC and PPC was near zero for all animals, both before initiation and after initiation. The plot shows the proportion of recordings versus phase differences in degrees.
(G) Pairwise spectral Granger causality was calculated on the median LFP in each brain area during the sustained attention period (left) and after touch (right). Bi-directional effective connectivity in the theta range and bottom-up effective connectivity in the beta frequency range were evident during the attention period. Both of these forms of communication are decreased in the period after touch. The lines represent mean across recordings, shaded areas represent ± 1 SEM.
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7. Figure 5
Spiking Activity in PFC Exhibited Long-Range Phase Locking to PPC 5 Hz Oscillation
(A) Spike-LFP phase locking was used to test if theta phase organized spiking activity across areas. The schematic shows that only a uni-directional long-range relationship was found between PPC theta phase and PFC spiking activity.
(B) An example unit recorded in PFC exhibited phase locking to PPC 5 Hz activity. The polar plot shows histogram of preferred phase of firing (in degrees).
(C) Combined across recordings for Animal A, spike-LFP phase locking was most prominent at a narrow band centered on 5 Hz, with a large fraction of units exhibiting significant spike-LFP phase locking. Spike-LFP phase locking was present throughout the duration of the trial and did not exhibit task-dependent modulation in strength. See Figure S5 for other animals.
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8. Figure 6
Both Theta and High Gamma Activity Were Involved in the Local Organization of Spiking Activity in PFC
(A) Spike-LFP phase locking was calculated between the 5 Hz oscillation and spiking activity, both in PFC.
(B) An example unit recorded in PFC exhibited phase locking to PFC 5 Hz activity. The polar plot shows preferred phase of firing, same unit as Figure 5B.
(C) PFC units exhibited local and long-range spike-LFP phase locking to the 5 Hz oscillation. The Venn diagram indicates the percentage of units across all animals that exhibited local locking to PFC phase, long-range locking to PPC phase, or both local and long-range locking.
(D) Spike-LFP phase locking was calculated between high-gamma activity and spiking activity, both in PFC.
(E) An example unit recorded in PFC exhibited phase locking to broad high-gamma activity.
(F) Across recordings for Animal A, units were predominantly phase locked to oscillations at 5 Hz and activity in the high gamma band.
(G) Across recordings for Animal A, the average Rayleigh’s Z for significantly locked units (a measure of the strength of phase locking) was also highest for spike-LFP phase locking at 5 Hz and in the high gamma range.
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9. Figure 7 Spiking Activity in PPC Was Coupled to High Gamma Activity
(A) Spike-LFP phase locking was calculated between high-gamma activity and spiking activity, both in PPC.
(B) Across recordings in Animal C, units were predominantly phase locked to high-gamma activity. In contrast to PFC, no prominent spike-LFP phase locking was seen at 5 Hz.
(C) An example unit recorded in PPC exhibited phase locking to broad high-gamma activity.
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